Mechanism for actuating the needle bar and thread puller in a sewing machine



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O m R J COURT ET AL MECHANISM FOR ACTUATING THE NEEDLE BAR Filed Nov.27, 1951 March 29, I955 AND'THREAD FULLER IN A SEWING MACHINE UnitedStates Patent MECHANISM FOR ACTUATm G THE NEEDLE BAR AND THREAD PULLERIN A SEWING MACHINE Jean Court, Chatelaine-Geneva, and Ramon CasasRobert,

Geneva, Switzerland, assignors to Mefina S. A., Binnmgen, Switzerland, acorporation of Switzerland Application November 27, 1951, Serial No.258,332 Claims priority, application Switzerland January 22, 1951Claims. (Cl. 112241) This invention relates to sewing machines and moreparticularly has reference to a mechanism for actuating the needle barand thread take up.

The actuating mechanism for the to and fro or reciprocating movement ofthe needle bar and thread take up of a sewing machine usually comprisesa horizontal shaft arranged in the arm of the sewing machine andcarrying a crank to which is connected one end of a connecting rodhaving its other end connected to the needle bar. The thread take up,when it is of the articulated type, is driven by a crank pin usuallycarried by the crank which actuates the needle bar.

To obtain the necessary time lag or interval between the movements ofthe needle bar and the thread take up, the crank pin actuating thelatter is angularly displaced relatively to the crank pin actuating theneedle bar.

In one type of prior art needle bar and articulated thread take upactuating mechanism for sewing machines, the horizontal crank pincarrying shaft and the reciprocable vertical needle bar are located inthe same plane and the main crank pin has one end of the needle barconnecting rod connected directly thereto. The crank pin also has fixedthereto a plate which in turn carries a thread take up actuating crankpin, the axis of which is angularly displaced from the axis of the maincrank pin about the axis of said shaft to provide for the required lagor interval between the operation of the needle bar and the thread takeup necessary to enable the thread take up to continue delivery of threadto the needle and the shuttle after the needle has been withdrawn fromthe material being sewn.

One disadvantage of such type of mechanism is that the crank carryingthe two crank pins and the plate fixed on the main crank pin andcarrying the thread take up actuating crank pin are of complicated anddelicate construction which renders the mechanism expensive.

In other types of prior art needle bar and articulated thread take upactuating mechanisms for sewing machines a single crank pin or two crankpins having a common axis are carried by the horizontal shaft forreciprocating the needle bar and actuating the thread take up.

Since in these machines the movements of the needle bar and of thethread take up are not relatively displaced in order that a certainlength of thread may still be delivered to the shuttle after the needlehas been withdrawn from the material to be sewn, it is necessary to havethe thread slide over a guide placed in its path between the eye of thethread take up and the needle.

This guide is thus an additional element and expensive to provide.Furthermore, it is a cause of friction and wear of the thread betweenthe feed bobbin and the nleedlg, which may lead in some cases tobreakage of the t rea On the other hand, it should be noted that in theabove mentioned prior constructions, the geometric axis of thehorizontal shaft actuating the needle bar and the thread take up and thegeometric axis of the needle bar itself, are arranged in one and thesame plane.

An object of the present invention is to provide a mechanism foractuating a needle bar and a thread take up of a sewing machine whichavoids the disadvantages of the prior art mechanisms.

Another object of this invention is to provide a mechanism for actuatinga needle bar and a thread take up of a sewing machine, in which theconnecting rod for reciprocating the needle bar is pivotally connectedto a crank pin carried by a horizontal shaft, and the thread 2,704,987Patented Mar. 29, 1955 take up is pivotally connected to a crank pincarried by said horizontal shaft, the two crank pins having the sameaxis and in which the needle bar is disposed a distance from thevertical plane passing through the axis of said horizontal shaftcarrying the crank pins sutflcient to produce a time lag or intervalbetween the movements of the needle bar and the thread take up.

Other objects will appear in the following description and drawings.

To facilitate the understanding of the present invention regerfince ismade to the accompanying drawings in w 10 Fig. 1 is a diagrammatic endelevation view of a needle bar and thread take up actuator of a knowntype.

Fig. 2 is a side elevational view of a portion of the mechanism shown inFig. 1.

Fig. 3 is an end elevation of the head of a sewing machine with partsremoved to show the drive mechanism for the needle bar and thread takeup constructed according to the present invention.

Fig. 4 is a detailed fragmentary view in front elevation of themechanism for actuating the needle bar and thread take up.

Fig. 5 is a view similar to that of Fig. 4 showing a modified form ofstructure.

In the device of known type shown in Figs. 1 and 2, the needle bar 1 andthe horizontal shaft 2 are located in the same plane. The shaft 2carries the crank 3, the crank pin 4 of which actuates the needle bar 1through a connecting rod 5.

The thread take up 6 is of the articulated type. An arm 7 pivoted on afixed pin 8 in the machine is connected at 9 to the middle portion ofthe thread take up 6. The foot of the latter is joined to a crank pin 10carried by the crank 3, and in the present case, by the crank pin 4, oneend of which is fixed to a small plate 11 on which is mounted the crankpin 10.

The angular displacement between the two crank pins 4 and 10 operates toretard the movement of the thread take up 6 relative to the movement ofthe needle bar 1 which is necessary so that the thread take up cancontinue to deliver thread to the shuttle after the needle has beenwithdrawn from the work material.

As illustrated in the drawings Figs. 3 to 5 the mechanisms according tothe present invention for imparting vertical reciprocating movement tothe needle bar 1 and the articulated thread take up 6 comprise ahorizontal shaft 2 mounted in the arm 12 of the sewing machine forrotation and carrying a crank. In the illustrated construction the crankis in the form of a fly wheel 13 on which is fixed a crank pin 4 forreciprocating the needle bar 1 through the intermediary of theconnecting rod 5.

Thread take up 6 is of the articulated type and has its foot or lowerend formed as a fork provided with two tines 6a. Each tine is providedwith a bore to receive the crank pin 4 so that the forked end of thethread take up can be mounted on the crank pin 4 with the tines 6adisposed on opposite sides of the connecting rod 4 as clearly shown inFig. 4.

The thread take up 6 is connected intermediate its forked end and itsfree or thread receiving end by a pivot 9 on the free end of an arm orlink 7. At its other end link 7 is mounted for rocking or pivotalmovement about a pivot 8 carried by a fixed part of the head of thesewing machine.

In the illustrated construction, this fixed part of the machine is ablock 14, attached by screw 15 to the machine frame. Since theillustrated sewing machine is adapted to elfect zigzag stitching, asdescribed in application Serial No. 84,608, filed March 31, 1949, nowPatent No. 2,682,845, dated July 6, 1954, the needle bar 1 isreciprocably mounted in a rocker 16 capable of rocking about a shaft 17fixed in a support block 18 attached by means of a screw 19 to themachine frame. The upper end of the shaft 17 is reciprocably mounted inthe block 14. By loosening the screw 19 it is possible to shift thesupporting block 18 transversely of the arm of the machine, whichoperation is facilitated by an eccentric device 20. The transverseshifting of the supporting block 18 produces an angular displacement ofthe shaft 17 and the block 18 about the axis of the screw 15.

The needle bar 1 also participates in the angular movement whereby it ispossible to regulate the position of the needle in a plane transverse tothe arm of the machine.

To prevent the oscillating movement of the needle bar 1 about the shaft17 being transmitted to the connecting rod when the machine is effectingsewing in zigzag or other ornamental fashion, the connecting rod 5 has anose 21 with a slot 22 therein which enables the rod to follow a guide23 formed by the edge of a plate 24 fixed to the machine frame.

As shown in Figure 4, the pivot 9 includes a stub pin 25 fixed in themiddle portion of the thread puller 6 and the arm 7 is mounted thereonwith the interposition o a porous metal sleeve 26 containing alubricant. In this manner this joint does not require periodiclubrication.

In the mechanism described, to permit the necessary time lag between themovements of the needle bar 1 and the thread take up 6, the needle bar 1is positioned at a sufiicient horizontal distance from the verticalplane passing through the geometric axis of the horizontal shaft 2.

Thus the needle reaches its lowest point at the instant when the axis ofthe crank pin 4 is in the plane passing through the geometric axis ofthe shaft 2 and the axis of the pin 5a connecting the connecting rod 5to the needle bar 1, and between these two axes.

In this position, which is that shown in Figure 3, the crank pin 4 hasnot reached its lower dead point nor has the foot of the thread take up.

The latter will not attain its lowest point until the crank pin 4occupies the position 4' shown in dotted lines in Figure 3, that is tosay, until the crank pin 4 will lie in the vertical plane passingthrough the horizontal shaft 2. Such an arrangement of the needle bar 1relatively to the shaft 2 produces an effective shift between themovements of the needle bar 1 and the thread take up 6 notwithstandingthat the connecting rod 5 and the foot of the thread take up 6 areconnected on the same crank pin 4. The path T of the eye of the threadtake up 6 is shown in dotted lines in Figure 3 and it will be seen thatthis path is particularly favorable since it has no substantiallylateral displacements and its general direction is inclined to the axisof the needle.

Figure 5 shows a modification of the actuating mechanism andparticularly with respect to the connection of the connecting rod 5 andlower end of thread take up 6 to the pin carried by the crank 3. In thismodification the crank pin on which the connecting rod 5 is pivoted isin the form of a sleeve 4a carried by the flywheel 13. The connectingrod 5 is provided with a bore for receiving the sleeve 4a as shown. Apin 27 is carried by the foot of the thread take up 6, and this pinprojects through the bore of the sleeve 40. An elastic washer 28 engagesin a groove 29 on the end of the pin 27 and serves to retain the pinwithin the sleeve 4a. This retains the thread take up in place and inturn the lower portion of the thread take up retains the connecting rodin place on the sleeve 40 between the flywheel 13 and the thread takeup.

It should be noted furthermore that in the case of application of thepresent driving mechanism to a machine of the type capable of makingzigzag and other ornamental stitching with a free arm and with a shuttlerotatably mounted on an axis substantially vertical, the arrangement ofthe horizontal shaft 2 and the needle bar 1 within spaced verticalplanes permits the upper arm of the machine to be located directly abovethe free lower arm.

Furthermore since the horizontal shaft 2 is in this case displacedlaterally in the upper arm, sufiicient space is left in the latter toinstall a lamp without it being necessary to provide on the said arm abulge for this purpose. For this reason, the general appearance of themachine is rendered more attractive.

From the foregoing, it will be realized that the mechanism of thepresent invention combines the advantages of each of the two knownmechanisms previously described, that is to say, the use of a crank witha single crank pin actuating both the needle bar and the thread take up.This arrangement eliminates, by reason of the displacement of the twovertical planes, one containing the geometric axis of the drive shaftand the other the geometric axis of the needle bar, the disadvantages ofthe said prior constructions and par icularly of the supplementary guideof the thread between the eye of the thread take up and the needle.

Having described our invention we claim:

1. A sewing machine comprising a head, a needle bar mounted in the headfor vertical reciprocating movement, a horizontal rotary shaft mountedin the head, a crank carried by said shaft, a connecting rod pivotallyconnected at one end to said needle bar and having its other endpivotally connected to said crank at a distance from the axis of saidshaft, a crank pin carried by said shaft, and an elongated articulatedthread take up having one of its ends pivotally mounted on said crankpin, and its other thread-engaging end free, a link pivotally connectedat one end to said head and pivotally connected at its other end to thethread take up between its ends to impart reciprocating movement to thefree end of the thread take up in a substantially vertical path, theaxis of the pivotal connection of the connecting rod to the crankcoinciding with the axis of the crank pin, said needle bar being spacedhorizontally from a vertical plane passing through the axis of thehorizontal shaft 21 sufiicient distance to provide a lag between theoperation of the needle bar and the thread take up so that the downwardmovement of the take up lags behind the downward movement of the needlebar.

2. A sewing machine according to claim 1 in which the end of the threadtake up connected to the crank pin is in the form of a fork with twotines and the end of the connecting rod connected to the crank isdisposed between said tines.

3. A sewing machine comprising a head, a needle bar mounted in the headfor vertical reciprocating movement, a horizontal rotary shaft mountedin the head, a tubular crank pin carried by said shaft with its axiseccentric with respect to the axis of the shaft, a connecting rodpivotally connected at one end to said needle bar and having its otherend provided with a bore for receiving said crank pin to pivotallyconnect it to said crank pin for pivotal movement about the axis of saidcrank pin, an elongated articulated thread take up having a threadengaging free end, and a stud pin carried at the other end of saidthread take up and extending within the tubular crank pin to pivotallyconnect said end of the thread take up to said crank pin for pivotalmovement about the axis of said crank pin, a link pivotally connected atone end to said head and pivotally connected at its other end to thethread take up between its ends to impart reciprocating movement to thefree end of the thread take up in a substantially vertical path, theaxis of the pivotal connection of the connecting rod to the crankcoinciding with the axis of the crank pin, said needle bar being spacedhorizontally from a vertical plane passing through the axis of thehorizontal shaft a suflicient distance to provide a lag between theoperation of the needle bar and the thread take up so that the downwardmovement of the take up lags behind the downward movement of the needle4. A sewing machine comprising a head, a needle bar mounted in the headfor vertical reciprocating movement, a horizontal rotary shaft mountedin the head, a tubular crank pin carried by said shaft with its axiseccentric with respect to the axis of the shaft, a connecting rodpivotally connected at one end to said needle bar and having its otherend provided with a bore for receiving said crank pin to pivotallyconnect it to said crank pin for pivotal movement about the axis of saidcrank pin, an elongated articulated thread take up having a threadengaging free end, and a stub pin carried at the other end of saidthread take up and extending within the tubular crank pin to pivotallyconnect said end of the thread take up to said crank pin for pivotalmovement about the axis of said crank pin, a link pivotally connected atone end to said head and pivotally connected at its other end to thethread take up between its ends to impart reciprocating movement to thefree end of the thread take up in a substantially vertical path, theaxis of the pivotal connection of the connecting rod to the crankcoinciding with the axis of the crank pin, said needle bar being spacedhorizontally from a vertical plane passing through the axis of thehorizontal shaft a sufficient distance to pro vide a lag between theoperation of the needle bar and the thread take up so that the downwardmovement of the take up lags behind the downward movement of the needlebar, said stub pin being fixed at one of its ends to said thread takeup, and means on the other end of said stub pin to retain it within thecrank pin with the connecting rod interposed between the thread take upand the portion of the horizontal shaft carrying the crank pin.

5. A sewing machine comprising a head, a needle bar mounted in the headfor vertical reciprocating movement, a horizontal rotary shaft mountedin the head, a tubular crank pin carried by said shaft with its axiseccentric with respect to the axis of the shaft, a connecting rodpivotally connected at one end to said needle bar and having its otherend provided with a bore for receiving said crank pin to pivotallyconnect it to said crank pin for pivotal movement about the axis of saidcrank pin, an elongated articulated thread take up having a threadengaging free end, and a stub pin carried at the other end of saidthread take up and extending within the tubular crank pin to pivotallyconnect said end of the thread take up to said crank pin for pivotalmovement about the axis of said crank pin, a link pivotally connected atone end to said head and pivotally connected at its other end to thethread take up between its ends to impart reciprocating movement to thefree end of the thread take up in a substantially vertical path, theaxis of the pivotal connection of the connecting rod to the crankcoinciding with the axis of the crank pin, said needle bar being spacedhorizontally from a vertical plane passing through the axis of thehorizontal shaft a suflicient distance to provide a lag between theoperation of the needle bar and the thread take up so that the downwardmovement of the take up lags behind the downward movement of the needlebar, said stub pin being fixed at one of its ends to said thread takeup, and provided with a groove in its circumferential surface at theother end thereof, and a resilient washer mounted in said groove toretain the stub pin within the crank pin with the connecting rodinterposed between the thread take up and the portion of the horizontalshaft carrying the crank pin.

References Cited in the file of this patent UNITED STATES PATENTS842,161 Ammerman Jan. 29, 1907 946,019 Diehl Jan. 11, 1910 20 2,173,320De Voe Sept. 19, 1939 FOREIGN PATENTS 139,866 Great Britain July 14,1920

